Method of making diaphragms



, JR., ETAL IAPHRAGMS A118- 19, 1941- P. l.. CLARK Patented Aug. 19, 1941 METHOD' oF MAKJNG nmnnadrrs Percy L. c1ark,J.,`G1encoe, and Carl Waterbury,

f Chicago, Ill.,` l

Application Aprilzs, 1939, serial N0.,27o,53o

2 Claims,

Our inventionrelates to vaginalV diaphragms and particularly to a methodof making such diaphragms. a

"Diaphragms ofthe class described are pro-` vided` with stiifening or reinforcing elements in the rim thereof, one tyleutilizing a coil of spring wire and the other, or Mensinga type, utilizing a hat spring. A drawback in the manufacture ofsuch diaphragms arises out of` the diflicultyof centering the reinforcing element in the body of rubber constituting the rim. In case the spring member is not centered ar portion thereof will be exposed andy render the diaphragm unlit for use.

A method of molding in which certain of the diiiculties are overcome `is disclosed in the patentgto John T. Clark, No. 2,111,313 of March 15, 1938, but this method has objections that have been overcome in the method herein disclosed.

The predominant thoughtin connection with thepresent improvement is to provide for exact centering of the reinforcing annulus, whereby the diaphragm maybe accurately molded in oom--` pleted form with the exception of an area of substantially 9,0 degrees of the diameter of the rim, this area being so disposed as to render. it easy; to apply liquid rubber thereto by hand.

The location of the open or incompleted section of the rim is properly determined by a considerationlof the forces generated by the die in the act of distributing the raw rubber used in the molding operation; in other words, the metal annulus should be seated in a recess so located that the` force of the flowing rubber `willtend to seat the annulus more firmly in the recess rather i than to tend to dislocate it. With this consideration in `mindI have provided in the lower or male die a seat located outwardly of the arc of curvature of the dome, above the lower limits of the rim groove and not above the transverse axis of the metal reinforcing element. In the case of the spirally wound annulus this serves to define the seat as extending over approximately 90 degrees and located at the lower, outer corner of the rim space. In this position the rubber that is ejected with considerable force and velocity out of the dome cavity into the rimcavity tends to urge the annulus against its seat rather than to displace it. Furthermore, since the coils composing the annulus are spaced apart, the rubber will readily Iiow directly into and through the coil without being compelled to change direction.

The resulting product is a completely molded diaphragm having at an outer edge a narrow aboutI one quarter` of the circumferencel of the rim. Such Iachannel while itcanhot be lledby dipping therim `in liquid rubber can be Aquickly lled by hand using a small rod orIstylu's through which the rubber is transferred to the `channel and allowed to? run along` its length and distribute itself evenly therein.

, `Inthe case of diaphragins using'the flat spring asa reinforcement the described improvement is o1' still greater importanceQWith the seatlocated as` before described thefrim is so molded'as to 1leave bare the bottomand a portion of the lower outer edge of the metal band, a substantial lip of rubber extending inwardly below the lower edge ofthe band. This insures that in applying the liquidl rubber in the' finishing operation there will becomplete and even Vcoverage of the band and `a round peripheral edge-somethingY that cannot be secured where theu lower edge of the'band is seated 'in a recess in the mold.

channel extending over In that case the bottomV edge and theftwo adjacent sides are bare following the moldingoperation-anda round coating of even thickness can-Y not be applied. inlanymanner'other than by' a second molding operation. It will be understood that the reason advanced. for the4 use of the Mensinga diaphragm. vis that itfgives great rigid-` ityfagainst` lateral. distortion; thatis, it may be readily ,bent out of circularl form but cannot be bent out ofla plane. `To 'obtain this result the two metal bands constituting 'the annulus should be ofA substantial widthrelative to their thick-v ness-something like a clockspringf When so constructed 'therim' cannot be made circular in cross section without using a' great'excess'of material,` butshouldgbe-in the4 form' of afat oval;` in Wimanfequa-l thickness of rubber on 'au sides: -Suchfarirn"str1.lct1irecan only be pro-l duced in the manner shown herein; that is, where the molding operation results in the -formation of a quarter-round channel, which, due to surface tension or capillarity of the liquid rubber, may be lled evenly and with a round contour.

The invention will be more readily understood by reference to the accompanying drawing, in which:

Fig. 1 is a plan view of a diaphragm such as contemplated;

Fig. 2 is a sectional View through a pair of dies arranged in accordance with our invention;

Fig. 3 is an enlarged fragmentary sectional view of one portion of the dies;

Fig. 4 is an enlarged sectional view through to the groove formed in the rim, the groove having been partly lled by rotation of the diaphragm in a counter-clockwise direction.

TheV diaphragm in question has a dome rIII and a rim I I containing an annulus of metal acting asV Y,

a reinforcement. f

In molding the article we provide an upper or female die I2 and a lower or male dial-3, the die cavity I4 providing for the molding of the dome and ,thercavity I5 for the molding of the rim.. vThe ,difficulty in the construction of molded diaphragms has .been that of insuring perfect centering of the metal reinforcement and .to over,

come this diiculty we provide at the outer,.lower portion lof the rim cavity a seat I6, best shown in Figs. 2 and 3, on which is located an endless coil of wire I1, the respectiveturns of wire being spaced apart. It will be noted' that the annular'space between the shoulders I8-I'9 that defines the extent of the seat is substantially 90 degrees of the circumference of the rim. Thus in the molded product, as shown in Fig. 4, the groove in the rim represents about one quarter of the circumference.

The position of the seat is such that, as indi-V cated inFig. 3, the body of rubber which is supplied to the mold and which is indicated at in Fig. 2 iscaused to flow downwardly fand outwardly Aand tov spread into the rim cavity as indicated by the arrows in Fig.' 3. The force and velocity'of the raw rubber is considerable and thedirection of iiow is such that the metal annulus is' held `firmly against the seat, the rubber `*passing through the coils andfilling the cavity completely. i

In the construction shown in Figs. 5 and 6, which illustrate the manufacture of Mensinga diaphragms, 'thelower mold' 2l has a recess 22 that is slightly undercut to receive the two at leaf springs 23'constituting the reinforcement.

in Fig. 4, since in each thereof there remains after the molding operation a quarter round groove that may readily be lled with liquid rubber. In practice, after the molded product hasV been cured, the diaphragm is held in an inclined position by grasping the dome as shown in Fig. 1 and a quantity of liquid rubber is applied by a stylus or similar instrument 24 in such manner that it fills the groove as indicated by dotted lines in Figs. 4 and 6 and any excess runs along the groove. Thus in the finally completed product there is no possibility of an imperfect article; that is, one in which the metal reinforcement is exposed or not covered with an adequate thickness of rubber. The annulus being held in a definite position, it is certain to be covered fully on all of its sides except for the quarter round The upper mold 24 is substantially the same as that shown in Fig. 2. -As the rubber is squeezed into the rim -cavity the force thereof willtend to press the flat spring outwardly Vinto'the undercut space and thus effectually preventany rise of the annulus in the cavity. The resulting product shown in Fig. 6 is the same in all essentials as that shown 'bare section, and this being covered by individual hand'work, is easily filled due to the shape and location of the groove.

In the Mensinga diaphragm itis important to note that this arrangement provides that the lower edge of the fiat springs is not open ,on both sides, since it would beimpractical Vif not iin--V possible to Vcause the liquid rubber to flow around the projecting metal body. It shouldV be understood in4 examining Figs.` 3 to 6 that the Views are very greatly enlarged and that some'of the dimensions are exaggerated; for example, the flat springs in the Mensinga dia phragm are about the vthickness ofpaper; 'Y Weclaim: ,Y

1. The method of making a diaphragmhaving a metal reinforcement in its rim, which consists in pressing raw rubber between dies to mold the article in one operation and exposing said reinforcement through an open groove around said rim, said groove being located at a side of aver-s an annulus of metal in its rim which consists in supporting the annulus in a mold insuch` position that the iiow of rubber laterally outward toward the rim under the pressure of themolding dies tends to hold the annulus in its seat, the annulus being bare in the molded product to the extent of the width of jthe seatV therefor and less than one-half of the diameter thereoffthen curing the-molded product, and then, by a manual operation, running liquid rubber into the open space around said rim. f Y Y Y PERCY L. CLARK, JR.

CARL WATERBURY. s

e Y 2. The method of making a diaphragmfhaving 

